[PATCH v3 09/20] avocado/tasst: Add helpers to run commands with nstool

[David Gibson <david@gibson.dropbear.id.au>]

Use our existing nstool C helper, add python wrappers to easily run
commands in various namespaces.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 Makefile                |   7 +-
 avocado/tasst/nstool.py | 182 ++++++++++++++++++++++++++++++++++++++++
 avocado/tasst/site.py   |  16 +++-
 3 files changed, 202 insertions(+), 3 deletions(-)
 create mode 100644 avocado/tasst/nstool.py

diff --git a/Makefile b/Makefile
index fc83cd2..9add0a4 100644
--- a/Makefile
+++ b/Makefile
@@ -298,10 +298,13 @@ cppcheck: $(SRCS) $(HEADERS)
 
 AVOCADO = avocado
 
-avocado-%:
+avocado-assets:
+	$(MAKE) -C test nstool
+
+avocado-%: avocado-assets
 	PYTHONPATH=./avocado $(AVOCADO) run avocado --filter-by-tags=$*
 
-avocado-all:
+avocado-all: avocado-assets
 	PYTHONPATH=./avocado $(AVOCADO) run avocado
 
 # Default avocado tests to run, everything except the "meta" tests
diff --git a/avocado/tasst/nstool.py b/avocado/tasst/nstool.py
new file mode 100644
index 0000000..020e8a0
--- /dev/null
+++ b/avocado/tasst/nstool.py
@@ -0,0 +1,182 @@
+#! /usr/bin/python3
+
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# tasst - Test A Simple Socket Transport
+#         library of test helpers for passt & pasta
+#
+# tasst/nstool.py - Run commands in namespaces via 'nstool'
+#
+# Copyright Red Hat
+# Author: David Gibson <david@gibson.dropbear.id.au>
+
+import contextlib
+import os
+import sys
+import tempfile
+
+import avocado
+from avocado.utils.process import CmdError
+
+from tasst import Tasst
+from tasst.site import IsolatedSiteTasst, SiteTasst, Site, REAL_HOST
+from tasst.typing import typecheck
+
+# FIXME: Can this be made more portable?
+UNIX_PATH_MAX = 108
+
+
+class NsToolSite(Site):
+    NST_BIN = './test/nstool'
+
+    def __init__(self, name, sockpath):
+        if len(sockpath) > UNIX_PATH_MAX:
+            raise ValueError('Unix domain socket path \"{}\" is too long'.format(sockpath))
+
+        super().__init__(name)
+        self.sockpath = sockpath
+
+    def __enter__(self):
+        self._pid = int(REAL_HOST.output('{} info -wp {}'.format(self.NST_BIN, self.sockpath), timeout=1))
+        return self
+
+    def __exit__(self, *exc_details):
+        pass
+
+    # PID of the nstool hold process as seen by the test host
+    def pid(self):
+        return self._pid
+
+    # PID of the nstool hold process as seen by another site
+    # (important when using PID namespaces)
+    def relative_pid(self, relative_to):
+        cmd = '{} info -p {}'.format(self.NST_BIN, self.sockpath)
+        return int(relative_to.output(cmd))
+
+    def _nst_cmd(self, cmd, sudo=False):
+        nst_args = self.sockpath
+        if sudo:
+            nst_args = '--keep-caps ' + nst_args
+        return '{} exec {} -- {}'.format(self.NST_BIN, nst_args, cmd)
+
+    def output(self, cmd, sudo=False, **kwargs):
+        return REAL_HOST.output(self._nst_cmd(cmd, sudo), **kwargs)
+
+    def fg(self, cmd, sudo=False, **kwargs):
+        return REAL_HOST.fg(self._nst_cmd(cmd, sudo), **kwargs)
+
+    def bg(self, cmd, sudo=False, **kwargs):
+        return REAL_HOST.bg(self._nst_cmd(cmd, sudo), **kwargs)
+
+
+# Create path for temporary nstool Unix socket
+#
+# The obvious choice would be to use Avocado's workdir, but that often
+# gives paths that are too long for Unix sockets
+def temp_sockpath(name):
+    tmpd = tempfile.mkdtemp(suffix=name)
+    return os.path.join(tmpd, 's')
+
+
+class UnshareSite(NsToolSite):
+    def __init__(self, name, unshare_opts, parent=REAL_HOST, sudo=False):
+        sockpath = temp_sockpath(name)
+        parent.require_cmds('unshare', self.NST_BIN)
+
+        super().__init__(name, sockpath)
+
+        self.parent = typecheck(parent, Site)
+        self.holdcmd = 'unshare {} -- {} hold {}'.format(unshare_opts,
+                                                         self.NST_BIN, sockpath)
+        self.sudo = typecheck(sudo, bool)
+
+    def __enter__(self):
+        self.holder = self.parent.bg(self.holdcmd, sudo=self.sudo)
+        self.holder.__enter__()
+        return super().__enter__()
+
+    def __exit__(self, *exc_details):
+        super().__exit__(*exc_details)
+        
+        try:
+            self.parent.fg('{} stop {}'.format(self.NST_BIN, self.sockpath))
+        finally:
+            self.holder.__exit__(*exc_details)
+
+        try:
+            os.remove(self.sockpath)
+        except FileNotFoundError:
+            pass
+
+        os.rmdir(os.path.dirname(self.sockpath))
+
+
+class UserNetNsTasst(IsolatedSiteTasst):
+    """
+    Test creating a userns+netns together
+
+    :avocado: tags=meta
+    """
+
+    def setup_site(self):
+        return UnshareSite(type(self).__name__, '-Ucn')
+
+    def test_userns(self):
+        REAL_HOST.require_cmds('capsh')
+        with self.setup_site() as ns:
+            ns.require_cmds('capsh')
+            capcmd = 'capsh --has-p=CAP_SETUID'
+            self.assertRaises(CmdError, REAL_HOST.fg, capcmd)
+            ns.fg(capcmd, sudo=True)
+
+
+class NestedNsTasst(IsolatedSiteTasst):
+    """
+    Test creating userns with a netns nested within
+
+    :avocado: tags=meta
+    """
+
+    @contextlib.contextmanager
+    def setup_site(self):
+        name = type(self).__name__
+        with UnshareSite(name + '.userns', '-Uc') as userns:
+            with UnshareSite(name + '.netns', '-n', parent=userns, sudo=True) as netns:
+                yield netns
+
+
+class PidNsTasst(IsolatedSiteTasst):
+    """
+    Test unsing unshare -p  to create a pidns
+
+    :avocado: tags=meta
+    """
+
+    def setup_site(self):
+        return UnshareSite(type(self).__name__, '-Upfn')
+
+    def test_relative_pid(self):
+        with self.setup_site() as site:
+            # The holder is init (pid 1) within its own pidns
+            self.assertEquals(site.relative_pid(site), 1)
+
+
+class ConnectNsToolTasst(SiteTasst):
+    """
+    Test connecting to a pre-existing nstool
+
+    :avocado: tags=meta
+    """
+
+    @contextlib.contextmanager
+    def setup_site(self):
+        sockpath = temp_sockpath(type(self).__name__)
+        holdcmd = '{} hold {}'.format(NsToolSite.NST_BIN, sockpath)
+        with REAL_HOST.bg(holdcmd) as holder:
+            with NsToolSite("fake ns", sockpath) as site:
+                yield site
+
+        try:
+            os.remove(sockpath)
+        finally:
+            os.rmdir(os.path.dirname(sockpath))
diff --git a/avocado/tasst/site.py b/avocado/tasst/site.py
index 6450944..900e945 100644
--- a/avocado/tasst/site.py
+++ b/avocado/tasst/site.py
@@ -101,6 +101,19 @@ class SiteTasst(Tasst):
             self.assertIn('lo', site.ifs())
 
 
+class IsolatedSiteTasst(SiteTasst):
+    """
+    Test a site with isolated network (loopback only)
+
+    :avocado: disable
+    :avocado: tags=meta
+    """
+
+    def test_isolated_net(self):
+        with self.setup_site() as site:
+            self.assertEquals(site.ifs(), ['lo'])
+
+
 # Represents the host on which the tests are running, as opposed to
 # some simulated host created by the tests
 class RealHost(Site):
@@ -129,7 +142,8 @@ class RealHost(Site):
             proc.start()
             yield proc
         finally:
-            proc.stop()
+            if proc.poll() is None:
+                proc.stop()
 
 
 REAL_HOST = RealHost()
-- 
@@ -101,6 +101,19 @@ class SiteTasst(Tasst):
             self.assertIn('lo', site.ifs())
 
 
+class IsolatedSiteTasst(SiteTasst):
+    """
+    Test a site with isolated network (loopback only)
+
+    :avocado: disable
+    :avocado: tags=meta
+    """
+
+    def test_isolated_net(self):
+        with self.setup_site() as site:
+            self.assertEquals(site.ifs(), ['lo'])
+
+
 # Represents the host on which the tests are running, as opposed to
 # some simulated host created by the tests
 class RealHost(Site):
@@ -129,7 +142,8 @@ class RealHost(Site):
             proc.start()
             yield proc
         finally:
-            proc.stop()
+            if proc.poll() is None:
+                proc.stop()
 
 
 REAL_HOST = RealHost()
-- 
2.40.1